Light-weight composites are commonly used in manufacturing cars with lighter weight and improved fuel economy. The composites typically contain a structural layer made of a fiber reinforced cured polyester resin. The structural layer may be produced by compression molding. Protective coatings may be added after demolding to give the composites a finish and surface appearance appropriate for the end use. The composites are currently produced using expensive steel tools and technologically advanced compression molding machines.
Alternative methods of producing light weight composites can be utilized. Open tool molding is an example of such a method. To obtain a reasonable surface appearance, the process requires the use of a gel coat followed by a supporting composite laminate. In the process, a mold surface is first cleaned, a mold release coating is optionally applied, and a layer of a gel coat is applied and partially cured. A laminate is then applied to the gel coat layer, and the laminate and gel coat are cured to form a unitary part having a surface defined by the cured gel coat. Molded parts can be produced by this method to have a finish bearing any desired color originally carried by the gel coat.
In some applications, in order to obtain a smooth surface finish on the gel coat and reduce the extent of fiber read through, a barrier coat may be applied between the gel coat and the laminate. It would be desirable to produce low density, flexible barrier coats for such an application.